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Joined: Jul 2004
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G
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The NEC deals with that in the sections that deal with cords and fixture wires.

The basic rule is that 18ga (0.823 mm2) is big enough to operate the 15 or 20a overcurrent device with a bolted fault. The cord still has to be matched to the load as part of the listing.


Greg Fretwell
Joined: Apr 2015
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H
New Member
Just think about a blender with a 14 or 16 ga cord plugged into a 20 amp kitchen outlet. Same difference and legal.

Joined: May 2002
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Originally Posted by Texas_Ranger
[quote=HotLine1]Tex:
Doesn't work in the UK since 32 A isn't suitable for short-circuit protection of 0.75 mm2 and BS1363 power strips aren't designed for 32 A.

Tex, Remember in the UK the BS1363 power strip is fed through a fused plug - fuse is usually 13A but occasionally less - the one feeding my computer right now says 10A. That light's fine cable would also be fed through a BS1363 plug fitted (hopefully!)with a 3A - or less- fuse.

Joined: Dec 2001
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T
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Originally Posted by Hutch
Originally Posted by Texas_Ranger
[quote=HotLine1]Tex:
Doesn't work in the UK since 32 A isn't suitable for short-circuit protection of 0.75 mm2 and BS1363 power strips aren't designed for 32 A.

Tex, Remember in the UK the BS1363 power strip is fed through a fused plug - fuse is usually 13A but occasionally less - the one feeding my computer right now says 10A. That light's fine cable would also be fed through a BS1363 plug fitted (hopefully!)with a 3A - or less- fuse.


I think that was actually my point, you need the fuse in the plug not only for overload protection but also for short-circuit protection of the appliance flex and power strip. In case of a Euro table lamp or similar device you still don't need a fuse in the plug, even though the flex isn't suitable for carrying 16 amps at all.

Joined: Aug 2008
Posts: 62
A
andey Offline OP
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Guys, thank you very much for all your responses. I must admit that after reading the first few answers some time ago, and seeing that it's an unclear situation, i forgot about this thread.
I am surprised it's really like that.
So you can plug a 15 amp rated power strip into a 20 amp outlet, plug in some devices and have it running at 20 amp summarized load with breaker not moving and the wire overloaded by 33% ??
For the machine (designed to be ran on a nema 5-15 or 5-20 outlet), we decided to use #14 wire and put a 15 amp fuse right at our infeed, so we protect the cord even when plugged into a 20 amp.

But doesn't this topic lead to melting cheap power strips used on 20 amp outlets all the time? What's the US standard gauge for an average 5 or 6way residental power strip?

And what is your maximum permitted current for a non-fixed appliance on 5-15 (for example a vacuum cleaner, electric bbq or whatever)??

We also do have power strips with thermal problems, but usually they only melt when constantly overloaded. Our standard outlet is 16 amp, but only few people know it's officially "16 amp intermittent, 10 amp permanent" so they use a power strip to run two 2000 watt appliances, which is just under 20 amp and might never trip the 16a breaker.

Last edited by andey; 05/26/15 12:31 PM.
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This is a flaw in the listing of the power strip, not a problem with the receptacle you plugged it into.
Most will have a breaker in them and in a commercial installation it is required. Most places will have a fire marshal/life safety officer, enforcing that.


Greg Fretwell
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